A transformer has become a must-have circuit element for various kinds of electric appliance. Referring to FIG. 1, a conventional transformer principally comprises a magnetic core assembly 1, a winding frame 2, a primary winding coil (not shown), a secondary winding coil (not shown), and an enclosure. The primary winding coil and the secondary winding coil are wounded around the winding frame 2 and interact with the magnetic core assembly 1 to achieve the object of voltage regulation. The magnetic core assembly 1 is generally shaped as an EI-type core or an EE-type core. The enclosure 3 is made up of a bottom plate assembly 31 and a seal plate 32. When the bottom plate assembly 31 and the seal plate 32 are assembled, the magnetic core assembly 1 and the winding frame 2 can be fixedly positioned within the inner space enclosed by the bottom plate assembly 31 and the seal plate 32, and thereby construct the body of a transformer.
Referring to FIG. 1 again, the winding outlets of the primary winding coil and secondary winding coil that are wounded around the winding frame 2 are soldered together with a plurality of copper wirings 21, 22, 23 that are wrapped by polyvinyl chloride (PVC) film. Each of the free ends of the copper wirings 21, 22, 23 is provided with a stationary terminal, and each of the stationary terminals is used to secure the copper wirings 21, 22, 23 to the through holes on a print circuit board (not shown), thereby an electric connection can be established between the transformer and the printed circuit board. Alternatively, the transformer can be secured to the housing of an electric appliance or a printed circuit board depending on the requirements of circuit design.
The assembling process of a conventional transformer is described as follows: As shown in FIG. 2(a), the primary winding coil (not shown) and the secondary winding coil (not shown) are wounded around the winding frame 2, wherein the material of the primary winding coil and the secondary winding coil is preferably selected from copper wires. Next, the portions of the transformer windings wounded around the winding frame 2 are wrapped by a tape 24. Meanwhile, four winding outlets 25, 26, 27, 28 of the transformer windings will be led out from the winding frame 2. Next, as shown in FIG. 2(b), the first winding outlet 25 is soldered together with a first copper wiring 21 wrapped by a PVC film, the second winding outlet 26 is soldered together with a second copper wiring 22 wrapped by a PVC film, and the third winding outlet 27 and fourth winding outlet 28 are soldered together with a third copper wiring 23 wrapped by a PVC film, wherein the third and the fourth winding outlet 27 and 28 can be respectively led out from the primary winding coil and the secondary winding coil.
In order to prevent the bare portions of the three copper wirings from contacting with each other and prevent each solder point from piercing the insulating PVC film and causing the transformer to become short-circuited and finally burn out, the bare portions of the copper wirings are isolated from each solder point by tapes and pads according to prior art, and then the first winding outlet 25 and the first copper wiring 21 are folded upward and wrapped with one or several tapes 291 or a pad 292 so as to cover the bare portions of the copper wirings and solder points. Next, the second winding outlet 26 and the second copper wiring 22 are folded upward and wrapped with one or several tapes 293 or a pad 294 so as to cover the bare portions of the copper wirings and solder points. Finally, the third winding outlet 27 and the fourth winding outlet 28 as well as the third copper wiring 23 are folded upward and wrapped with one or several tapes 295 or a pad 296. Next, the free ends of each copper wiring 21, 22, 23 are tied with stationary terminals, such that these copper wirings 21, 22, 23 are secured and electrically connected to the printed circuit board.
The rest assembling process of the transformer are described as follows. Referring to FIG. 1 again, the magnetic core assembly 1 and the winding frame 2 with transformer windings clung thereto are coupled together and fixedly fit into the bottom plate assembly 31. After the seal plate 32 is mechanically cooperated with the bottom plate assembly 31 to enclose the magnetic core assembly 1 and the winding frame 2 and the supporting pins are bent and fixed, the whole transformer is immersed into a petrolatum solution. After the baking process performed to the transformer is finished, the whole manufacturing process of transformer is completed.
Subsequently, the stationary terminals of the copper wirings 21, 22, 23 are inserted into the through holes (not shown) on the printed circuit board, in order that an electric connection can be established between the transformer and the printed circuit board.
However, it can be understood from the above statements that the conventional assembling process of transformer needs numerous tapes and pads, and the transformer formed thereby is quite complicated in structure and require a costly manufacturing budget. More disadvantageously, the operations of wrapping the tapes and pads need to be done iteratively, and thus these operation become difficult to handle and the manufacturing yield of transformer can not be promoted further. In addition, each of the winding outlets (copper wires) are needed to be soldered with a corresponding copper wiring, and quality of the transformer will be debased because of the problems that the solder points pierce the insulating film. What is worse, the insulating film of the copper wiring is made up of PVC having a comparatively low melting point (about 105° C.), so that the durability against temperature for the transformer will be limited. Furthermore, each of the free ends of the copper wirings can not be directly secured to the printed circuit board, and thus the stationary terminals and the operation of processing the stationary terminals are required. In view of the above disadvantages, the conventional assembling process of a transformer not only squanders many materials in manufacturing and disburse more cost on manufacturing process, but also complicates manufacturing steps and lowers manufacturing yield.